Hydraulic turning joint

ABSTRACT

Disclosed is a hydraulic turning joint which has substantially reduced longitudinal length with an equal number of oil passages therein and can reduce the mounting space in the equipment and which improves the work efficiency, accuracy and reliance of the product. The hydraulic turning joint includes a shaft, a housing for rotatably and closely accommodating the shaft, at least one oil supply passage formed in the shaft, said oil supply passage longitudinally passing through the shaft, and at least one oil discharge passage formed on the top of the the housing, said oil discharge passage being correspondingly communicated with at least one oil supply passage, wherein each of said oil supply passages are transversely communicated with each of said oil discharge passages on the same plane. The hydraulic turning joint further includes sealing means installed between the oil discharge passages within the housing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hydraulic turning joint, and moreparticularly, to a hydraulic turning joint used for jointing upper andlower frames of equipment such as excavators, cranes, etc., wherein theupper frame is swingably jointed to the lower frame.

2. Description of the Prior Art

In construction equipment such as excavators or cranes, an upper frameis swingably jointed to a lower frame and for this jointing, a hydraulicturning joint is used as a jointing means.

More particularly, the hydraulic turning joint should joint the upperframe and lower frame of equipment such that not only the upper framecan be rotated smoothly relative to the lower frame, but also oil canflow between the upper and bottom frames through the hydraulic turningjoint. That is, the hydraulic turning joint should provide an oilpassage for the supply of a pressurized oil discharge from a hydraulicpump installed on the lower frame, to an actuator of each working member(in case of the excavator, a boom, an arm, a bucket, etc.) installed onthe upper frame.

In a conventional hydraulic turning joint, as shown in FIG. 1, a shaft102 coupled to a lower frame is rotatably and closely accommodatedwithin a housing 101 coupled to an upper frame. The inside of the shaft102 is formed with a plurality of oil supply passages 103a˜103e, and thehousing 101 is formed with a plurality of oil discharge passages104a˜104e, each of which is in communication with each of the abovementioned oil supply passages 103a˜103e. Furthermore, sealing slots105a˜105c are formed at various places (between the oil passages) of theinner circumferential surface of the housing 101 to provide a seal, andsince the sealing members 106a˜106c are mounted in the sealing slots105a˜105c, the sealing action can be performed between each of theadjacent oil passages 104a˜104e. By means of the hydraulic turning jointconstructed as mentioned above, not only the upper frame can beswingably jointed to the lower frame, but also the oil can flow betweenthe lower frame and the upper frame.

However, conventional hydraulic turning joints as mentioned above havethe disadvantages that, as the number of the oil passages in creases,the longitudinal length of the hydraulic turning joint becomes longerthan its transverse length. As a result, it is difficult to have enoughspace for mounting the above mentioned hydraulic turning joint in theequipment.

Further, conventional hydraulic turning joints have another disadvantagethat, since the length of the housing is relatively longer than thediameter of the housing 101, the inner circumferential surface of thehousing 101 has to be machined from both ends to the central section ofthe housing 101, rather than be machined at a time through either thetop end or the bottom end. This creates a degraded roughnecks on theinner circumferential surface, resulting in increased work time tofinish the surface, a reduction in work efficiency and a possiblelowering in the reliability of the entire product.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a hydraulic turningjoint which has substantially reduced longitudinal length with an equalnumber of oil passages therein.

It is another object of the present invention to provide a hydraulicturning joint which can reduce the mounting space in the equipment andwhich improves the work efficiency, accuracy and reliance of theproduct.

In accordance with an aspect of the present invention, there is provideda hydraulic turning joint adapted for swingably jointing an upper framerelative to a lower frame and for enabling an oil flow between saidupper and lower frames, the hydraulic turning joint comprising: a shaftcoupled to said lower frame; a housing coupled to said upper frame, forrotatably and closely accommodating said shaft; a plurality of oilsupply passages formed in said shaft, said oil supply passageslongitudinally passing through said shaft; and a plurality of oildischarge passages formed on the top of the said housing, said oildischarge passages being correspondingly communicated with said oilsupply passages; wherein said oil supply passages are transverselycommunicated with said oil discharge passages on the same plane.

Further, in accordance with another aspect of the present invention,there is provided a hydraulic turning joint adapted for swingablyjointing an upper frame relative to a lower frame and for enabling anoil flow between said upper and lower flames, the hydraulic turningjoint comprising: a first turning joint including a first shaft coupledto said upper frame, a first housing coupled to said lower frame, saidfirst housing accommodating said first shaft rotatably and closely, aplurality of first oil supply passages formed in said first housing, anda plurality of first oil discharge passages formed in said first shaft,said first oil supply passages being correspondingly communicated withsaid first oil discharge passages; and a second turning joint includinga second shaft coupled to said first housing and accommodating saidfirst housing closely therein, a second housing coupled to said firstshaft and accommodating said second shaft rotatably and closely therein,a plurality of second oil supply passages formed in said second shaft,and a plurality of second oil discharge passages formed in said secondhousing, said second oil supply passages being correspondinglycommunicated with said second oil discharge passages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view of a conventional hydraulicturning joint.

FIG. 2 is a schematic view of a preferred embodiment according to thepresent invention where, FIG. 2A is a section view, FIG. 2B is a topview and FIG. 2C is a bottom view.

FIG. 3 is a cross-sectional schematic view of another preferredembodiment according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 2A, 2B and 2C show the hydraulic turning joint of a preferredembodiment of the present invention. Referring to FIG. 2A, 2B and 2C,the shaft 1 coupled to the lower frame (not shown) is rotatably andclosely accommodated within the housing 3 coupled to the upper frame(not shown). The shaft 1 is formed with a plurality of oil supplypassages 5a˜5e inside of it which pass through from the top to thebottom end of the shaft 1, and the housing 3 is formed with a pluralityoil discharge passages 7a˜7e on its top such that each of the oildischarge passages 7a˜7e can be in communication with each top of theabove mentioned oil supply passages 5a˜5e. Therefore, on the same plane,each of the oil supply passages 5a˜5e formed in the shaft 1 can betransversely communicated with each of the oil discharge passages 7a˜7eformed on the housing 3.

Also, the grooves 9a and 9b are formed at predetermined positions of theouter circumferential surface of the shaft 1 and the engaging apertures11a and 11b are formed at predetermined positions on the side of thehousing 3, corresponding to the grooves 9a and 9b. By means of the balls13a and 13b and the bolts 15a and 15b, some parts of the balls 13a and13b being supported within said grooves 9a and 9b and the other partsthereof being supported within said engaging apertures 11a and 11b, andthe bolts 15a and 15b being engaged with the engaging apertures 11a and11b and supporting the balls 13a and 13b to prevent the balls fromseparating therefrom, the above mentioned shaft 1 and housing 3 can bejointed together without being separated from each other. Since each ofthe sealing slots 17a˜17d is formed between the adjacent oil passages7a˜7e of the inside of the housing 3, and each of the sealing members19a˜19d are inserted in the sealing slots 17a˜17d, the sealing actioncan be performed between each of the adjacent oil passages.

Also, the sealing slots and the sealing members can be disposed insidethe top of the above mentioned shaft 1.

In the hydraulic turning joint of this embodiment constructed asmentioned above, since, on the same plane, the oil supply passages 5a˜5eformed in the shaft can be transversely communicated with the oildischarge passages 7a˜7e formed on the housing 3, the increase in thenumber of oil passages does not result in an increase of longitudinallength in the hydraulic turning joint.

In addition, FIG. 3 shows the hydraulic turning joint according toanother embodiment of the present invention. Referring to FIG. 3, afirst shaft 51 and a first housing 53 act as one turning joint (thefirst turning joint), and, a second shaft 55 and a second housing 57 actas the other turning joint (the second turning joint).

That is, the first turning Joint is composed of the first shaft 51,which is coupled to the upper frame (not shown), and the first housing53, which is coupled to the lower frame (not shown) for rotatably andclosely accommodating the first shaft 51. And, the second turning jointis composed of the second shaft 55 and the second housing 57, the secondshaft 55 is jointed to the above mentioned first housing 53 by means ofbolt 61 and closely accommodating the first housing 53 therein and thesecond housing 57 is jointed to the above mentioned first shaft 51 bymeans of a bolt 59 for closely accommodating the second shaft 55therein.

In the hydraulic turning joint of this embodiment, the first shaft 51,the first housing 53, the second shaft 55 and the second housing 57 areconcentrically arranged by turns. The first housing 53 has the first oilsupply passages 63a and 63b formed inside of it. Each of the first oilsupply passages 63a and 63b is in communication with each of the firstoil discharge passages 65a and 65b formed within the first shaft 51. Thesecond shaft 55 has the second oil supply passages 67a and 67b formedinside of it, and each of the second oil supply passages is incommunication with each of the second discharge passages 69a and 69bformed within the second housing 57.

Since the inner circumferential surface of the first housing 53, whichis tangential to the outer circumferential surface, is formed betweenits first oil supply passages 63a and 63b mentioned above with thesealing slots 71a and 71b and the sealing members 73a and 73b areinserted in the sealing slots 71a' and 71b, the sealing action can beperformed between each of the first oil supply passages 63a and 63b.

In the same manner, since the inner circumferential surface of thesecond housing, which is tangential to the outer circumferentialsurface, is formed between its second oil discharge passages 69a and 69bmentioned above with the sealing slots 75a and 75b and the sealingmember 77a and 77b are inserted in the sealing slots 75a and 75b, thesealing action can be performed between each of the second oil dischargepassages 69a and 69b.

The hydraulic turning joint of this embodiment constructed as mentionedabove is composed of a dual shaft and a housing, and since the oilpassage to supply an oil between the upper and the lower frames aredistributed in the dual shaft and the housing, the entire length will besubstantially reduced with equal numbers of oil passages. Furthermore,the above mentioned first oil supply passages 63 and 63b and second oilsupply passages 67a and 67b can supply different pressurized oil throughthe first oil discharge passages 65a and 65b, and the second oildischarge passages 69a and 69b respectively, and can use oil and air atthe same time. That is, for example, the first supply passages 63a and63b and the first discharge passages 65a and 65b can be used forproviding off, while the second supply passages 67a and 67b and thesecond discharge passages can be used for providing air simultaneously.

As explained above, the hydraulic turning joint of the present inventioncan reduce its length with equal numbers of the oil passages therein asa conventional hydraulic turning joint and can improve the finishing ofthe inner surface of the housing. As a result, the hydraulic turningjoint can have a profitable mounting space within the equipment and canimprove the accuracy and the performance of the product. Particularly,the improved accuracy ensures the sealing action between each of the oilpassages. Furthermore, it is possible to use oil and air at the sametime with the separated dual turning joint.

What is claimed is:
 1. A hydraulic turning joint adapted for rotatablyjointing an upper frame relative to a lower frame and for enabling anoil flow between said upper and lower frames, the hydraulic turningjoint comprising:a first turning joint including a first shaft coupledto said upper frame, a first housing coupled to said lower frame, saidfirst housing accommodating said first shaft rotatably and closely, aplurality of first oil supply passages formed in said first housing, anda plurality of first oil discharge passages formed in said first shaft,and first means for sealing said first oil supply passages forcorrespondingly communicating with said first oil discharge passages;and a second turning joint including a second shaft coupled to saidfirst housing and accommodating said first housing closely therein, asecond housing coupled to said first shaft and accommodating said secondshaft rotatably and closely therein, a plurality of second oil supplypassages formed in said second shaft, and a plurality of second oildischarge passages formed in said second housing, and second means forsealing said second oil supply passages for correspondinglycommunicating with said second oil discharge passages.
 2. A hydraulicturning joint as claimed in claim 1, wherein said first means forsealing comprises groove means with a seal therein between said firstoil supply passages within said first housing.
 3. A hydraulic turningjoint as claimed in claim 1 or 2, wherein said second means for sealingcomprises groove means with a seal therein comprising another sealingmeans installed between the second oil discharge passages within saidsecond housing.
 4. A hydraulic turning joint as claimed in claim 1wherein said oil discharge and said oil supply passages in said firstshaft, said first housing and said second shaft include a longitudinalportion disposed along the longitudinal axis of the turning joint and atransverse portion disposed transverse to said longitudinal axis.
 5. Ahydraulic turning joint as claimed in claim 4 wherein said oil supplypassages in said second shaft comprise two passages whose longitudinalportions are disposed at differing distances from the longitudinal axisof the turning joint.